The present invention relates to a device for applying surface pressure to advancing workpieces like sheets of wood-based material and similar products in which at least one revolving compression belt can be pressed against the workpiece by a pressure medium hose that can be introduced into a pressure chamber, which is adjacent to the belt and sealed off with a sealing strip, whereby the sealing strip is introduced by a holder in a groove in a pressure plate and the compression belt is positioned in such a way as to slide along the sealing strip.
Whereas the pressure medium, compressed air for example, in one device of this type advances the holder and sealing strip perpendicular to the surface of the compression belt, the compressed air in the pressure chamber generates as it acts on the lateral surface of the sealing strip a force that parallels the surface of the compression belt. Since this force is expressed at the holder in the form of a moment that causes the holder to tilt inside the groove, the compressed air can no longer displace the holder in relation to the pressure plate. The sealing strip can accordingly no longer follow the deviations of the compression belt out of its plane that occur during pressing, resulting in narrow gaps between the compression belt and the sealing strip through which compressed air can escape out of the pressure chamber.